Obtenção de pastas por meio do método do pseudo-simplex-duplo para dosagem do CAA

Abstract

This research aims to improve and validate the method obtaining paste for dosage of SCC through the pseudo double simplex with three different types of mineral addition (metakaolin, rice husk pozzolan and limestone filler). First, content limits were defined for the paste components and then 17 paste compositions were produced. Mini cone tests were made, which generated spreading and T115 results. These were submitted to the R and F test and variance analysis to verify the reliability results obtained and represent these data in simplex coordinates to obtain the region with high probability occurrence of self-compacting pastes. Viscosity test (Marsh cone) and exudation (decanting method in a beaker) were used to verify the resistance to segregation of the pastes. Subsequently, the dosage followed with the composition of selfcompacting mortars to obtain the fine aggregate content and to compose three SCC mixtures, each with their respective mineral addition and paste content (weak, medium and strong). In addition, 7 SCC mixtures were produced directly from the constitutive paste for each mineral addition through a 2² factorial design with three central points, in which the paste volume and B/A ratio were configured as input variables to the system and these parameters were defined and compared with EFNARC (2005) for enframe or at least to come close to what the standard determines. The 30 SCC mixtures were subjected to fill capacity (slump flow and J-ring), viscosity (T500 and V Funnel), passing ability (L box) and segregation resistance tests by the sieve method. Then, compression strength tests were performed at 3, 7, 28 and 90 days, and ultrasonic pulse velocity at 28 and 90 days. As a result of research, it was possible to represent the results of the mini cone test (spreading and T115) in simplex coordinates and through the intersection between these variables to obtain a region with high probability occurrence of self-compacting pastes. In addition, from constituent pastes chosen in these regions, it was possible to obtain self-compacting mortars and concrete, according to the EFNARC (2005) parameters. Regarding mechanical strength, all CAA mixtures reached resistance greater than 40 MPa at 28 days, according to the objectives initially established in the project associated with the optimum ultrasonic pulse speed.